2000 GMC Sierra Trailer wiring

OK so I have a six wire and need to go seven to the new trailer. I have a brake controller plug under the dash and a six wire harness to the back. Is it possible to replace the 6 wire with a 7 wire from the dealer or is this a major mistake to even think about?

Thanks

[SomeStrangeGuy]

edit: nevermind.


what kind of trailer is it? does it have interior utilities that require the 7th wire or is that just how it came?

edit2: Click Me if you don't mind a trip to walmart. actually link is weird, reference part ## R74645

Originally Posted by SomeStrangeGuy

edit: nevermind.


what kind of trailer is it? does it have interior utilities that require the 7th wire or is that just how it came?

edit2: Click Me if you don't mind a trip to walmart. actually link is weird, reference part ## R74645

The trailer comes with 7 wires, I will know more when I look at the docs and get the meter out etc. So I would need a 6 to 7 (not seen one yet). However I think the seventh wire is for charging the brake battery and maybe lights. The truck comes stock with a 6 wire harness to the back however there is an option of 7. I thought there is a chance that it is wired and I just need to get the other harness from GMC.

Anyway I am figuring it out and thought a site member might have a similar setup since Chevy's and GMCs (after 2000 I think) are the same setup and lots of folks probably have trailers for bikes or camping here

[G-Force Junkie]

6 wire to the back??? I'm not familiar with GMC wiring...usualy vehicles have a standarf 4 prong, or the 7 prong. The 7 prong just adds a 12v for battery charging (8-10 gauge black), a blue for trailer brakes, and a orange for backup lights. If you already got brake controller harness in the cab, it usualy has 4 wires.

[G-Force Junkie]

Check this out http://www.etrailer.com/faq/wiring.asp
sounds like you need to run a 12v wire fronthe battery to the rear of your truck. There are wiring diagrams for this on the 'net, I'll see if I can find it. Use a 8 or 10 ga wire.

[G-Force Junkie]

...actualy, it appears the 6 wire would work, its only missing the auxlurity wire...what is typicaly used for back up lights. But considering 99% of trailers (unless we are talking boat trailers) with electric brakes have 7 pin, I would convert yours. It should only take rewiring at the bumper and tapping into the reverse lights wire.

[SomeStrangeGuy]

Originally Posted by sheepofblue

So I would need a 6 to 7 (not seen one yet). However I think the seventh wire is for charging the brake battery and maybe lights.

did you click the link above?

Congrats on the trailer. Can't help ya with the wiring, the trailer place installed mine since I only had 4 pin, and did the brake controller too. I've only seen 4 and 7 pin. 6, huh. Good luck with it!

I looked and while mine is a six and I have 6 in the harness I only use 4 right now. Looks like it is time to string wire Etrailer also had info on my truck specific but I was hoping to swap a harness rather than string wire for slickness of install

[SomeStrangeGuy]

Originally Posted by sheepofblue

I looked and while mine is a six and I have 6 in the harness I only use 4 right now. Looks like it is time to string wire Etrailer also had info on my truck specific but I was hoping to swap a harness rather than string wire for slickness of install

what the hell am I missing?? I've done just about anything you can do electrically to a car and I'm still confused . Can you draw a diagram

Originally Posted by SomeStrangeGuy

what the hell am I missing?? I've done just about anything you can do electrically to a car and I'm still confused . Can you draw a diagram

It is confusing. 2000 GMCs came two ways, with tow package and w/o
The 'with' is a 7 pole connector wired complete just plug a brake controller in and go.
The without (aka mine) has wiring exposed above the spare tire with 6 wires although i have found out 2 of the 6 are for weird things. This is easily connected to a 4 pole system. Also the truck is wired to accept a controller in the cab. What I wanted was to get the OEM 'with' wiring harness and plug it into my truck. Thus I would have a poor man's tow package (I already have the hitch reciever). However I have been told by the dealer that although the cab is wired for a brake controller the existing wiring is not able to have the HD tow package harness added. I am going to look at my truck an the Helm's Manual a bit more but figure I will have to drag some wire to the back from the fuse box.

[SomeStrangeGuy]

Originally Posted by sheepofblue

It is confusing....I am going to look at my truck an the Helm's Manual a bit more but figure I will have to drag some wire to the back from the fuse box.

I gotcha now I think, and I think you may be missing the fuses and terminals that the HD has. But yeah you're on the right track, as the primary diff between 6/7 wires is that the 7 has an extra 'power' wire to run onboard aux. equipment. From what I can recall this is usually rated no less then 20a.

BillAce may have more experience with this then I, but then again the question is not a complex orchestration of thiele-small params. rather simple 12vdc with current limiting.

Did I ask what kind of trailer yet?

...and in the end I highly recommend sourcing an all out re-kit rather the just adding some conductors to the existing. Just cleaner and neater, and since the labor is the same price

Originally Posted by SomeStrangeGuy

I gotcha now I think, and I think you may be missing the fuses and terminals that the HD has. But yeah you're on the right track, as the primary diff between 6/7 wires is that the 7 has an extra 'power' wire to run onboard aux. equipment. From what I can recall this is usually rated no less then 20a.

BillAce may have more experience with this then I, but then again the question is not a complex orchestration of thiele-small params. rather simple 12vdc with current limiting.

Did I ask what kind of trailer yet?

...and in the end I highly recommend sourcing an all out re-kit rather the just adding some conductors to the existing. Just cleaner and neater, and since the labor is the same price

That is why I wanted the whole harness, about $90 but it would have been cleaner and more reliable. I have a link at etrailer.com with instructions but it is not as clean.

The trailer is a Shadowmaster and if the ice storm doesn't screw the roads over to bad I will have pics tommorow

Update: My harness came in. Not only will it hook into the existing wiring and fuse box it comes with some fairly detailed instructions. Anyone that is looking to wire up a GMC/Chevy from 2000 up should consider this route.

[abtech]

Originally Posted by G-Force Junkie

...actualy, it appears the 6 wire would work, its only missing the auxlurity wire...what is typicaly used for back up lights. But considering 99% of trailers (unless we are talking boat trailers) with electric brakes have 7 pin, I would convert yours. It should only take rewiring at the bumper and tapping into the reverse lights wire.

The aux wire is also used for interior lights on enclosed trailers.